溫血魚

Is fish blood（血） cold or warm？ Most fish have cold blood. But moonfish（月亮魚） are the first known（已知的） fish with warm blood.

Moonfish live in the deep ocean. Its very cold there. Fish usually move slowly there. But warm-blooded（溫血的） moonfish swim fast. This is good for them to catch food.

Moonfish are rare（稀有的） to see. Fishermen（漁夫） think it is good luck（好運(yùn)） to see one. When they catch one， they dont sell（賣） it. They often give it away（贈(zèng)送） to friends.